This invention relates to a turntable apparatus having a vertically movable turntable, more specifically to a turntable apparatus well adapted to a reproducing apparatus for signals recorded on a disc.
Generally, in a reproducing apparatus for signals recorded on a disc, a video disc, for example, is set on a turntable, and a reproducing stylus is brought into contact with the video disc to reproduce information recorded on the disc. The information is composed of video and audio signals, and is recorded with very high density according to PCM (pulse code modulation) recording system. Therefore, if any foreign matters, such as dust, dirt from the hands, etc., stick to the video disc, reproduction cannot be performed with success, involving noise in reproduced pictures. Accordingly, there have been developed various kinds of apparatus which are provided with means for enabling us to set on and remove the video disc from the turntable without directly touching the disc.
Hereupon, the video disc is contained in a casing opening on one side, enclosed with a holder which is locked to the casing. In this state, the video disc is inserted into the reproducing apparatus from one side thereof on which a casing inlet opening is provided. When the insertion is completed, the video disc with the holder is held in the reproducing apparatus, and the holder is unlocked and disengaged from the casing. When the casing is removed from the apparatus, the video disc and the holder slip out from one side of the casing to remain in the reproducing apparatus, thus making the casing empty. In this state, reproducing operation is started. When the empty casing is inserted into the reproducing apparatus from the one side thereof after the reproducing operation is completed, the video disc with the holder is put into the casing from the one side thereof, and the holder is locked to the casing. Then, when the casing is removed from the reproducing apparatus, both the video disc and the holder are taken out from the reproducing apparatus as they are held together in the casing.
In order to accomplish the aforesaid operation, the turntable to bear the video disc can move vertically so that it may be located below the plane along which the video disc is inserted in the nonreproducing mode, that is, below the casing inlet opening provided on the apparatus and that it may be moved up to carry only the video disc thereon in the reproducing mode. A turntable apparatus with such a turntable is generally constructed as shown in FIGS. 1 and 2. A chassis 10 is fitted with a bearing 12 penetrating the same. The bearing 12 supports a turntable shaft 14 so that the shaft 14 may move vertically and rotatably about an axis thereof. A turntable 16 is coaxially fixed on the upper portion of the turntable shaft 14. A center spindle 18 is coaxially coupled to the top end of the turntable shaft 14. As shown in FIG. 2, the center spindle 18 is intended to align the center of a video disc 20 placed on the turntable 16 with the axis of rotation of the turntable 16, so that the top surface of the center spindle 18 is located above the top surface of the turntable 16.
Therefore, a casing 21 containing the video disc 20 need be passed over the center spindle 18 which is located above the turntable 16. Namely, in the prior art turntable apparatus, the stroke of the vertical movement of the turntable 16 cannot help being considerable. Accordingly, the motor for moving the turntable 16 is subjected to heavy load, and the reproducing apparatus cannot be improved in compactness.